A super-resolution fluorescence microscopy using two-color laser beams was proposed. The microscopy is based on the combination of two-color fluorescence dip spectroscopy and a phase modulation technique for the laser beam. By applying the proposed technique to a laser-scanning microscope, a fluorescence image of a sample can be observed with a spatial resolution overcoming the optical diffraction limit. To demonstrate validity of the microscopy, we constructed a scanning microscope system using commercial nano-second pulse lasers. An image of micro beads containing dye molecules was observed by the microscopy. We succeeded in obtaining the image with a resolution overcoming the diffraction limit in nano-meter scale region. The experimental data showed that the resolution was improved three times at least. The microscopy is expected to be an appropriate analysis method for the samples with nano-meter scale structures.
By theoretical simulations we investigated the transport properties of oligoporphyrin molecular wires on assumption of the molecular bridge structures. It was found that the tape-porphyrin wires, where the macrocycles are linked by three C-C bonds aligned in parallel, show the metallic I-V curves, while the other conjugated porphyrin show the semiconducting I-V curves. These differences are found to originate from the differences of their HOMO-LUMO energy gaps. Next we studied the transport properties of the T-shape porphyrin wires where extra macrocycles are fused to the edge of the linear-shape tape-porphyrin molecules. The existence of the current loop is predicted in the vicinity of a metal cation site, which induces the magnetic field on top of it. It was also found that this magnetic field is useful in controlling locally the spin orientation of the metal atom, and has a detectable strength in an experiment. Finally we discussed the applicability of the current-induced magnetic field in the molecular devices such as unimolecular memories.
Accurate SIMS measurement of a boron profile in a SiO2-Si interfacial region under optimum incident angle of low-energy primary oxygen ion beam was made in order to demonstrate the mechanism of boron penetration through gate oxide. Degrees of ionization of Si and boron became almost equal in SiO2 and Si at the 20-degree incident angle with a practical sputtering rate. The estimation of an apparent shift of a boron profile toward surface and the determination of the SiO2-Si interface under measurement conditions achieving matrix-independent degree of ionization of Si were also examined. The SIMS measurement using optimum conditions revealed that the variation of flat band voltages was proportional to the variation of penetrating boron doses in the range of 0.85−1.30 V. It was also found that when a penetrating boron dose was equivalent to a flat band voltage over 1 V, the electrical activation of boron was lower than that of boron ion-implanted in a Si substrate.
We have deposited diamond-like carbon (DLC) films on Cu/PYREX glass and SiO2/Si substrates using RF magnetron sputtering techniques. Investigation was made on the structural and chemical bonding properties and on the thermal stability of the deposited films. The films were characterized by visible (514 nm) Raman spectroscopy and photoelectron spectroscopy using synchrotron radiation light. It has been found that the films deposited under typical sputtering conditions are amorphous carbon (a-C) with 62% sp2 (graphite-like) and 38% sp3 (diamond-like) bonds. Ordering of a-C has been observed with an increase in substrate temperature during deposition and after annealing, although the sp3/sp2 ratio in films does not change even up to 900oC. No conversion observed between sp3 and sp2 bonds indicates that the DLC films deposited by RF magnetron sputtering have higher thermal stabilities.
Recently, formaldehyde liberated from wallpapers, furnitures and adhesive agents in new buildings and houses cause troubles in human health, and this is called the sick building symdrome. In this study, the carbonaceous materials are prepared from coffee grounds by microwave treatment or by surface-treatments with two different silane coupling agents. We estimated the removal efficiency of formaldehyde by such materials. The water contents of coffee grounds are larger than those of other wastes and thus they were easily carbonized. Both the amount of formaldehyde adsorbed onto the carbonaceous materials and the adsorption rate increased with increasing microwave treatment period, and increased with increasing concentration of silane coupling agents, because the numbers of amino groups on the carbonaceous materials increase. The carbonaceous materials prepared from the coffee grounds would be utilized for adsorbates to remove formaldehyde.
A Li4Ti5O12 thin film electrode for rechargeable lithium microbatteries was prepared on Au substrate by a sol-gel method. A stable sol was successfully prepared by adding poly(vinylpyrrolidone) (PVP) into 2-propanol solvent, in which PVP prevented a crack formation. The sol was coated on Au substrates with a spin coater, and was converted to gel during the spin coating process. The gel was then heated to form Li4Ti5O12 oxide. Optimized conditions for preparation of uniform film without any cracks were firstly a heating temperature of 600oC, 3000 rpm, and secondly a sol with 5 mol% of PVP. An electrochemical cell was constructed with polymethylmethacrylate gel-polymer electrolyte, which was electrochemically evaluated using a cyclic voltammetry and a discharge and charge test. The discharge and charge curves were very flat around 1.55 V and the rechargeability increased up to 97.5% at 60th cycle. The Li+ ion diffusion coefficient at a potential of 1.57 V was estimated to be 6.5×10−10 cm2 s−1, indicating that the thin film exhibited a fast electrochemical response. From these results, it can be said that the Li4Ti5O12 thin film with a fast electrochemical response is a prospect of an active electrode material, and that PVP sol-gel method is very useful for thin film preparation.
We have grown extremely thin, single-domain 3C-SiC films by forming a low-temperature interfacial buffer layer using monomethylsilane (H3C-SiH3) on nominally on-axis Si(001) substrate, whose miscut is estimated to be less than 0.1−0.2o. We have clarified that single-domain 3C-SiC(001) 3×2 films can be grown on both Si(001) 2×1 single-domain and Si(001) 2×1 + 1×2 double-domain surfaces. The film is as thin as 45−200 nm, which is compared to the film as required in a previous study (> 5 μm) to achieve the single-domain 3C-SiC films on a nominally on-axis Si(001) substrate. The development of the single domain observed is understood in terms of electromigration during dc-resistive heating and unique adsorption nature of the monomethylsilane.
Energy transfer at D2O ice/CO/Pt(111) interface under the irradiation of NIR pulses (1064 nm) was studied by time-resolved sum-frequency generation (SFG). When the 140 bilayer (BL)-D2O ice/CO/Pt(111) interface was irradiated, the CO molecules were immediately heated by the energy transfer from the energy-deposited Pt substrate. However, the first 22 BL of ice, which was active for SFG, reached a maximum temperature at 500 ps. It was found that there was a 330 ps of time-response for the energy transfer from the Pt substrate to the first ice layer at the interface.
The well-ordered ultra-thin Al2O3 film was grown on a Cu-Al alloy for the first time. The growth was achieved by introducing oxygen at high substrate temperature in a ultra-high vacuum. The film showed (7/√3×7/√3)R30o LEED structure. The thermodynamics of the growth mechanism was discussed.